Compound drum mill



Oct. 26 1926.

A. ANDREAS COMPOUND DRUM MILL 3 Shee'ts-Shet 1 Filed Sept. 14

Oct. 26 I926. 15604;673

A. ANDREAS COMPOUND DRUM MILL Filed Sept. 14, 1925 s Sheet-Sheet 2 Oct.26 1926. 1,604,673

. Y A. ANDREAS COMPOUND DRUM MILL File p 14, 1925 3 she'ets-Shet 5Patented a. 26, 1926.

UNITED STATESPATENT OFFICE- ABNO ANDREAS, OI MUNSTEZB, GERMANY.

COMPOUND DRUM MILL.

Application filed September 14,1925, Serial No. 58,108, and in GermanyOctober ,11, 1924.

This invention is an improvement in that type of compound drum mills inwhich there are separate compartments for the prelim inary grinding andthe finer grinding of the material.

The main object of the invention is to provide a simple andautomatically acting mechanism for separating the coarser materialdelivered from the preliminary grinding compartment, and to return saidcoarser material to said compartment while separating out the finermaterial and advancing it to the next successive compartment in whichthe material is to be more finely ground.

In carrying out my invention I provide an arrangement of partitions,certain of them being solid and others being perfdrated, and

' an arrangement of screens whereby the rotation of the parts carryingsaid partitions and screens acts to automatically separatethe coarse andfine material and deliver the two grades in opposite directions, one tothe preliminary grinder, and the other'to the finer grinder. i

As one important feature of my invention 1 provide conducting chambersencircled by an annular compartment in which the screening of thematerial takes place. By means of radially arranged partitions in theconducting chambers, the latterare divided into compartments, and theannular screening compartment is likewise divided into chambers bysolidand screening partitions in such a way that the material isdelivered from one conducting chamber to the annular screen carryingcompartment, and the coarser particles are returned from. the latter tothe same conducting chamber, while the finer material is deliveredthrough the other conducting chamber.

As a further important feature the annular screening compartment withits screens may be so designed that the screen surface is considerablyincreased, and a more efliclent screening operation is'securedv This maybe accomplished by making the chamber of greater width than the distancebetween the grinding chambers and/or by settingthe transversely disposedscreen at an angle, whereby the screening surface is not only increased,but a double screenlng action is obtained during the rotation of theparts. The screens may be oblique to the drum axis, or approximatelytangential. v As a further important feature the screens are sopositioned and mounted that they may be readilyremoved from the exteriorfor replacement and repair.

As a further important feature certain of the chambers in the annularscreening compartment may be provided with guides, whereby comparativelysmall orifices may be employed for the entrance and delivery of thematerial.

Other important features and advantages of my improved construction willbe pointed out hereinafter, or will be apparent from a consideration ofthe specific constructions illustrated in the accompanying drawings. Inthese drawings: Fig.1 is a central longitudinal section of aconstruction embodying my invention.

Fig. 2 is a transverse-section on the line 2-2 of Fig. 1.

Fig. \3 is a development of a portion of the wallof the conductingchambers, and

showing the relationship of the outlet and inlet orifices to thescreening compartment. Fig. 4L is a central longitudinal section showinga modified form.

Fig. 5 is a transverse section on the line 5-5 of Fig. l.

Fig. 6 is a development of the wall of showing guides for directing thematerial to the outlet orifices, and

Fig. 10 is a detail showing the conducting guides in outline. I

My improved constructlon 15 adapted to 'be employed in any type ofrotary grinding mill, and between a preliminary grinding chamber a and afine grinding chamber 6. By the terms preliminary gnndmg and finegrinding I do not mean to lmply that the mill grinds in merely twostages, as there may be a series of grinding chambers, each= producing afiner grade of maternal, and my improved construction may be employedbetween each two successive grind ing chambers. I

In; Fig. 1 I hatpe shown two of these separators with the intermediategrinding chamber mainly broken away. The main drum has a pair of walls aand e forming therebetween a pair of conducting chambers 0 and d. Thepartition e between the conducting chamber 0 and the preliminarygrinding chamber a: is provided with slots or other apertures f for theentrance of the crushed material from the grinding chamber 01. to theconducting chamber 0. It also has a central opening for the return ofthe coarse particles which have not passed through the screenshereinafter referred to. The wall e between the conducting chamber d andthe fine grinding chamber 6 has merely a' central opening g, for thedelivery therethrough of the material which has assed through thescreens. The conducting chambers 0 and d are each subdivided into aplurality of chambers z bfy means of radiallyfextending partitions Thetwo chambers E and 01 may be separated by a transverse partition 6 thatis, a partition at right angles to the axis of rotation of the device.

E-ncircling the conducting chambers c and d is an annular compartment kwhich serves as the screening chamber. This is subdivided into aplurality of compartments 8 by radially disposed solid partitlons Z andintermediate screening partitions m. Thus each alternate partition inthe annular chamber k is solid, while the remaining ones are erforatedto serve as screens. The number of partitions in the annular compartmentis preferably double the number of chambers in each conductingcompartment, and each screen an comes approximately opposite to apartition h while the solid partitions ma come intermediate of twopartitions 71..

The peripheral wall of the conducting compartments, which serves as theinner wall for the annular screening compartment,

is provided with a series of orifices n and 0..

The orifices n communicate with the conducting compartment 0 and are infront of the screens m, while the orifices 0 are behind the screens andcommunicate with the conducting chamber d, as shown more particularly inthe development Figure 3. In the center of the ap aratus is a pair ofoppositely facing conicaFdeflectors for causing material which dropsthrough the orifices n and 0 to be deflected or directed to the openings9 and g, respectively.

The peripheral wall t of the annular screen compartment is may beprovided with openings adjacent to the several screens, and normallytightly closed bydoors or valves .2 whereby the screens may be removedfor cleaning or repair. In Fig. 2 I have indicated two of these sets ofscreen compartments with the delivery and receiving chambers, and haveindicated the screen in the second one as being of finer mesh than thatof the first one, considered in the direction of travel of the material.

Obviously these two may be spaced at any desired distance apart, andthere may be a series of them with successivel finer screens. I

In the operatlon of the construction hereinbe fore described, thematerial which is crushed in the preliminary grinding chamber a entersthe conducting chamber 0 through the slots f as indicated by arrows atthe lower left hand side of Fig. 1, and passes through the chambers 71and openings n into the screening chambers's. As the constructionrotates, the material is carried toward the upper side of the apparatuswhile the fine material falls through the screen or sieve into theadjacent chambers, and there after falls through the opening 0 into achamber 6 to the second conducting chamber d, whereby it is deflectedthrough the opening 9, by the deflector p. The coarser material whichhas not passed through the screens m returns through the OIJBIIIIITS 42when the latter are at the upper side oi: the apparatus, and is directedback to the preliminary grinding chamber a through the opening 9 by thedeflector 31. Thus the material is automatically separated into twogrades, the finer being advanced to the next grinding chamber, while thecoarser part is returned for regrindin The artitions e and a, may beprovide with pipes extending axially in opposite directions from theopenings 9 and g, so as to conduct the material away from the artitionsto the center of the grinding cham ers. This is more impnrtant for thepartition 6 as it prevents the immediate return of such material throughthe openings f.

To facilitate the introduction and removal of the screens m theperipheral wall may be provided with slots 1' normally closed by slidingvalve plates 2 as shown in Figs. 4, 5 and 6. At the lower portion ofFig. 4 I have shown one of these valve plates pulled out axially, andthe screen moved outward radially from its normal position.

In order to increase the area of the screening surface the screens m andthe solid partitions Z may be arranged obliquely, as indicated in Fig.6. The operation is substantially the same as hereinbefore described,except that due to the oblique setting of the screens the materialiscaused to travel along the screen through a greater distance, and moreeflicient screening operation is efiected. The efi'ective screeningaction may be also increased by making the screening chamber of greateraxial length than the distance be I tween the partitions e and e,, asshown in Fig. 4.

In Fig. 7 I have illustrated a further arrangement of screening andsolid partitions in the annular screen compartment. Here neoaera thescreens m. and partitions Zextend tangentially or approximatelytangentially. Thus as the material passes through an opening njat thelower side of. the apparatus, it will be caused to travel over thescreen as indicated by the arrow I,

y and as the device rotates clockwise the screen reaches such a positionthat the material travels in the opposite direction along the screen tothe same opening, as indicatedby the arrow II. The finer material passng through to the screen, falls on the partition n and is directed tothe opening 0. This movement of the material back and forth across thescreen insures a substantially com plete removal of the finer material.These screens and partitions need not be straight,

as indicated in the forms hereinbefore specifically referred to, but maybe curved and of an approximate tangential positioning as indicated inFig. 8

In order to direct the material to the openings 0 and insure thesubstantially complete return of the coarser particles, the

' solid partitions Z may be provided with guides or bafles as indicatedin Figs. 9 and 10. Metal plates w may be inclined 1n opposite directionsto each opening a, as shown in Fig. 10, and ma be curved 1n an areconnecting the radia partition and the peripheral wall t, as shown inFig. 9. These curved guides w may constitute the solid partitions andpermit-of the elimination of the straight radial partitions Z.

Having thus. described my invention, What ll claim as new and desire tosecure by Letters Patent is: 1

1. A compound drum mill having aperipheralwall encircling a preliminarygrmding chamber, and a fine grinding chamber, an annular screeningchamber encircling said wall and having transversely disposed screens,means for conducting to said sc reening chamber material from thepreliminary grinding chamber, means for delivering from said screeningchamber the material passing through said screens, and means forreturning to the preliminary grinding chamber the material which doesnot pass through said screens.

2. A rotary drum, mill having a preliminary grinding chamber, a finegrinding chamber in axial alignment therewith, an annular screeningchamber intermediate of said grinding chambers and encircling the drum,a conveying chamber for delivering material from said preliminarygrinding chamber to said screening chamber, and for returning to saidpreliminary grinding chamber the coarse material from the screeningchamber, and a conveying chamber for delivering fine material rom saidscreening chamber to said fine grinding chamber.

3. A compound drum mill including a preliminary grinding chamber and afine of axially spaced conductin tition,

screens, said drum having a pair of grinding chamber in axial alignment,an annular screening chamber having a plurality of transversely disposedscreens, and a pair chambers separated by a artition exten 'ngtransverse- 1y of the axis of the mill, one serving for the delivery ofmaterial from the preliminary grinding chamber to the screening chamber,and also for the return of coarse material from the screening chamber tothe preliminary grinding chamber and the other serving for the deliveryof fine material from the screening chamber-to the fine grindingchamber.

4. A rotary drum havin preliminary grinding an fine grinding chambers,an annular screening chamber encircling the drum between said grindingchambers and having transverse partitions extending in a directionhaving a radial component, and conducting chambers from each of saidgrinding chambers to said screening chamber.

5. A rotary drum havin preliminary grinding an fine grinding chambers,an annular screeningchamber encircling the drum between said grindinchambers, and having transversely dispose alternately arranged screensand solid partitions, a pair of conveying chambers axially spaced andseparated by a transverse parone connecting said preliminary grindingchamber and said screening chamber adjacent to one side of each of saidscreens, and the other connecting said fine grinding chamber and saidscreening chamber adjacent to one side of each of said solid partitions.

6. A rotary drum havin preliminary grinding an fine grinding chambers,an annular screening chamber encircling said drum between said grindingchambers, and having alternately arranged, transversely disposed screensand solid paraxially spaced axially spaced axially spaced titions,forming an annular row of compart ments, 3. pair of conveying chambersaxially spaced by atransverse partition, one connecting each alternatecompartment with said preliminary grinding chamber, and the otherconnecting the remaining compartments with the fine grindin chamber.

7. A rotary drum having exially spaced preliminary grinding and finegrinding chambers, three spaced, transverse partitions forming a pair ofintermediate conve 'ng chambers between said grinding chambers, anannular screening chamber encircling said conveying chambers and havinga cylindrical inner wall and transversely disposed, alternately arrangedsolid partitions and annular rows of apertures in said wall, oneconnecting one of said conducting chambers with said screening chamberat points adjacent to each screen,.and the other row connecting tralaperture and additional apertures, said drum having a preliminarygrmdingchamber adjacent to said last mentioned partition, and a fine grindingchamber on the opposite side of 'the other partition, the space betweensaid partitions servin as conductin chambers, and having ra ia'llydispose axially extending partitions, a screening chamber encircling thedrum and having alternately arranged, transversely disposed perforateand imperforate walls, the wall of said drum having a series ofapertures adjacent to the first mentioned partition and to the saidimperforate walls, and a second pair of apertures adjacent to the secondmentioned partition and the perforate walls. 9. A construction asdefined in claim 8, in which there are provided a pair of oppo= sitelyfacing, conical deflectors between said partitions, for directingmaterial through the central openings of said partitions. v

10. A construction as defined in claim 3, in which thescreening chamberis provided with openings and the screens are detachably mounted forremoval through said openings. 11. A construction as defined inclaim 3,

. in which the peripheral wall of the screening chamber is provided withslots adjacent to each screen, and movable members normally closing saidslots.

12. A compound drum mill having an im perforate transverse partition, apartition upon one side thereof and having a central aperture, apartition upon the opposite side thereof and having a central apertureand additional apertures, said partitions forming two axially s acedconducting chambers, a screening c amber encircling the drum and havingtwo rows of apertures, one communicatin with one conducting chamber andthe ot er communicating with the other conducting chamber, saidapertures being arranged alternately in a circumferential direction, andsaid screening chamber havin alternately arranged screens and partitionsdisposed between successive aper tures.

13. A compound drum mill including a preliminary grinding chamber, afine grindmg chamber, an annular screening chamber having two sets ofapertures in its inner Wall, a conducting chamber leading from one setof apertures to the preliminary grinding chamber, a conducting chamberleadlng from the other set of apertures to the fine griding chamber,transversely disposed screens in said screening chamber, transverselydisposed partitions in said screening chamber between successivescreens, and guides in said screening chamber for delivering coarsematerial to said first mentioned set of apertures.

14. A compound drum mill including a preliminary grinding chamber, afine grinding chamber, three axially spaced intermediate partitionsforming a pair of conducting chambers between said partitions, onecommunicating with the preliminary grinding chamber, and the other withthe fine grinding chamber, and an annular screening chamber encirclingsaid conveying chambers, and of greater axial length than the distancebetween said partitions.

Signed this 26th dayof August A. D. 1925.

ARNO ANDREAS.

